Owing to the large band gap energy of 3.2eV, pure TiO 2 film operates as an efficient photocatalyst under UV light irradiation and exhibits no photocatalytic activity under the visible spectral region. UV is only about 3% of the light existing in the solar spectrum. Currently, the red-shift in the band gap energy induced by dyemodified TiO 2 film is one of the most popular and economic processes for improving the drawback in TiO 2 photocatalyst. Therefore, we assess the photocatalytic efficiency of dye-modified TiO 2 thin film using various dye molecules such as Eosin Y, Safranine O and tris-2, 2β²-bipyridyl dichlororuthenium (II) hexahydrate (Rubpy) using the sol-gel process under visible light (Ξ» N 400 nm). These results showed that TiO 2 thin film modified with Safranine O dye had the best photodegrading efficiency under visible light irradiation. The photocatalytic inactivation of Safranine O and Eosin Y dye-modified TiO 2 thin films against phytopathogenic bacteria including Enterobacter cloacae SM1 and Erwinia carotovora subsp. carotovora 3 which cause severe soft/basal rot disease in vegetable crops in Taiwan were all more than 90% after irradiation with visible light for 60min. The evidence suggests that the dye-modified TiO 2 thin film under visible light irradiation has potential for plant protection applications in hydroponic systems.